Pulse dimming is usually adopted by CCFL Inverters. Generally there are two methods for pulse dimming. One method uses direct current (DC) input voltage, and the other method utilizes an external PWM input signal. For the first method, a comparison wave generator is required. By comparing a DC input signal with a reference comparison wave, a pulse dimming signal is generated. For the second method, the pulse dimming signal follows the PWM input signal directly, thus there is no need for a reference comparison wave generator. As a result, the two pulse dimming methods are not generally compatible.
For either of the two dimming methods, a separate circuit board is needed. Thus, in the prior art, two circuit boards are required, which adds to cost.